Gas molecules in amorphous silicon dioxide: origin, diffusion, spectroscopic properties and effect on material properties

Dr.habil.phys. Linards Skuja (ISSP UL Laboratory of Spectroscopy of Amorphous Materials)

Amorphous silicon dioxide – also known as glassy SiO2, or (popular, but incorrect) as "quartz glass" (amorphous SiO2, glassy silica, fused quartz) is one of the most important optical materials in applications requiring optical elements:

  • Very low light loss, for example, optical fiber wires for information transmission;
  • Ability to transmit high power continuous or pulsed laser radiation: materials processing, medicine, (nuclear) energy;
  • good transmission in the ultraviolet (UV) and vacuum UV regions of the spectrum: lenses, ultraviolet radiation sources, details of spectroscopic instruments;
  • Radiation resistance: nuclear, space engineering.

In practice, these properties of amorphous SiO2 are mainly influenced not by pure electron processes but by photo / radiochemical reactions with small gas molecules that can be incorporated into interstitial spaces between SiO4 tetrahedrons. The worksop will look at the properties of currently known interstitial gas molecules in SiO2, their impact on material properties, and the ISSP research in this area (*):

  • Hydrogen H2
  • Oxygen O2 (*)
  • Ozone O3 (*)
  • Nitrogen N2
  • Chlorine Cl2 (*)
  • Hydrogen chloride HCl
  • Fluoride F2(?)